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  Subjects -> ENGINEERING (Total: 2018 journals)
    - CHEMICAL ENGINEERING (161 journals)
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    - ENGINEERING (1135 journals)
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ENGINEERING (1135 journals)            First | 5 6 7 8 9 10 11 12 | Last

Magdeburger Journal zur Sicherheitsforschung     Open Access  
Magnetics Letters, IEEE     Hybrid Journal   (Followers: 3)
Management and Production Engineering Review     Open Access  
Management Science and Engineering     Open Access   (Followers: 1)
Manufacturing Engineer     Hybrid Journal   (Followers: 3)
Manufacturing Research and Technology     Full-text available via subscription   (Followers: 4)
MATEC Web of Conferences     Open Access  
Matériaux & Techniques     Full-text available via subscription   (Followers: 1)
Mathematical Models and Methods in Applied Sciences     Hybrid Journal   (Followers: 2)
Mathematical Problems in Engineering     Open Access   (Followers: 3)
Mathematics of Control, Signals, and Systems (MCSS)     Hybrid Journal   (Followers: 5)
Mauerwerk     Hybrid Journal  
Measurement     Hybrid Journal   (Followers: 1)
Measurement Science Review     Open Access   (Followers: 1)
Meccanica     Hybrid Journal   (Followers: 1)
Mechatronics     Hybrid Journal   (Followers: 4)
Medical and Biological Engineering and Computing     Hybrid Journal   (Followers: 2)
Medical Engineering & Physics     Hybrid Journal   (Followers: 9)
Membrane Science and Technology     Full-text available via subscription   (Followers: 2)
Membrane Technology     Full-text available via subscription   (Followers: 1)
Memetic Computing     Hybrid Journal  
Metal Powder Report     Full-text available via subscription   (Followers: 2)
Metallurgist     Hybrid Journal   (Followers: 2)
Metaphysica     Hybrid Journal   (Followers: 1)
Metascience     Hybrid Journal   (Followers: 1)
Metrologia     Full-text available via subscription   (Followers: 2)
Microelectronic Engineering     Hybrid Journal   (Followers: 4)
Microelectronics International     Hybrid Journal  
Microelectronics Journal     Hybrid Journal   (Followers: 5)
Microelectronics Reliability     Hybrid Journal   (Followers: 6)
Microfluidics and Nanofluidics     Hybrid Journal   (Followers: 9)
Micromachines     Open Access   (Followers: 1)
MNASSA : Monthly Notes of the Astronomical Society of South Africa     Full-text available via subscription   (Followers: 1)
Modelling and Simulation in Engineering     Open Access   (Followers: 4)
Modern Applied Science     Open Access   (Followers: 1)
Molecular BioSystems     Full-text available via subscription   (Followers: 1)
Molecular Engineering     Hybrid Journal  
Molecular Pharmaceutics     Full-text available via subscription   (Followers: 9)
MRS Bulletin     Full-text available via subscription   (Followers: 5)
MRS Online Proceedings     Full-text available via subscription   (Followers: 1)
Multiagent and Grid Systems     Hybrid Journal  
Multidimensional Systems and Signal Processing     Hybrid Journal  
NANO     Hybrid Journal   (Followers: 8)
Nano Letters     Full-text available via subscription   (Followers: 46)
Nano Research     Hybrid Journal   (Followers: 5)
Nano Reviews     Open Access   (Followers: 17)
Nanopages     Full-text available via subscription   (Followers: 1)
Nanoscale and Microscale Thermophysical Engineering     Hybrid Journal   (Followers: 3)
Nanoscale Systems : Mathematical Modeling, Theory and Applications     Open Access  
Nanoscience and Nanoengineering     Open Access  
Nanoscience and Nanotechnology     Open Access   (Followers: 2)
Nanoscience and Nanotechnology Research     Open Access   (Followers: 1)
Nanotechnologies in Russia     Hybrid Journal   (Followers: 1)
Nanotechnology     Hybrid Journal   (Followers: 9)
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 15)
Nanotechnology Reviews     Full-text available via subscription   (Followers: 5)
Natural Hazards     Hybrid Journal   (Followers: 258)
Nature Nanotechnology     Full-text available via subscription   (Followers: 46)
Naval Engineers Journal     Hybrid Journal   (Followers: 3)
NDT & E International     Hybrid Journal   (Followers: 13)
Nexo Revista Científica     Open Access  
Nigerian Journal of Technological Research     Full-text available via subscription  
Nigerian Journal of Technology     Full-text available via subscription  
NIR news     Full-text available via subscription  
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
Nonlinear Engineering : Modeling and Application     Full-text available via subscription   (Followers: 1)
Nova Scientia     Open Access  
NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin     Hybrid Journal   (Followers: 4)
Nuclear Engineering and Design     Hybrid Journal   (Followers: 12)
Numerical Algorithms     Hybrid Journal   (Followers: 2)
Numerical Heat Transfer, Part A: Applications: An International Journal of Computation and Methodology     Hybrid Journal   (Followers: 5)
Numerical Heat Transfer, Part B: Fundamentals: An International Journal of Computation and Methodology     Hybrid Journal   (Followers: 7)
Ocean Science Journal     Hybrid Journal   (Followers: 3)
Oil and Gas Journal     Full-text available via subscription   (Followers: 11)
Online Journal for Global Engineering Education     Open Access  
Open Journal of Antennas and Propagation     Open Access  
Open Journal of Applied Sciences     Open Access  
Open Journal of Fluid Dynamics     Open Access   (Followers: 3)
Open Journal of Safety Science and Technology     Open Access   (Followers: 5)
Operations Research Letters     Hybrid Journal   (Followers: 5)
Optical Communications and Networking, IEEE/OSA Journal of     Hybrid Journal   (Followers: 4)
Optimization and Engineering     Hybrid Journal   (Followers: 3)
Opto-Electronics Review     Hybrid Journal   (Followers: 1)
OR Spectrum     Hybrid Journal   (Followers: 1)
Organic Electronics     Hybrid Journal   (Followers: 3)
Ozone Science & Engineering     Hybrid Journal   (Followers: 1)
Papers In Regional Science     Hybrid Journal   (Followers: 6)
Particle & Particle Systems Characterization     Hybrid Journal  
Particulate Science and Technology: An International Journal     Hybrid Journal   (Followers: 1)
Perspectives on Science     Hybrid Journal   (Followers: 4)
Pesquisa Operacional     Open Access  
Pest Management Science     Hybrid Journal   (Followers: 5)
Petroleum Science     Full-text available via subscription   (Followers: 2)
Phase Transitions: A Multinational Journal     Hybrid Journal  
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences     Full-text available via subscription   (Followers: 5)
Physica B: Condensed Matter     Hybrid Journal   (Followers: 5)
Physica C: Superconductivity     Hybrid Journal  
Physica D: Nonlinear Phenomena     Hybrid Journal   (Followers: 3)
Physics of Fluids     Hybrid Journal   (Followers: 24)
Planning News     Full-text available via subscription   (Followers: 3)

  First | 5 6 7 8 9 10 11 12 | Last

Journal Cover Reactive and Functional Polymers
   [6 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1381-5148
     Published by Elsevier Homepage  [2575 journals]   [SJR: 0.834]   [H-I: 55]
  • Improving the mechanical resistance of waterborne wood coatings by adding
           cellulose nanofibres
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Stefan Veigel , Gerhard Grüll , Stefan Pinkl , Michael Obersriebnig , Ulrich Müller , Wolfgang Gindl-Altmutter
      In the present study, microfibrillated cellulose (MFC) and nanocrystalline cellulose (NCC) were applied as additives for a waterborne acrylate/polyurethane-based wood coating in order to improve the mechanical resistance of coated wood surfaces. Coating mixtures containing up to 5wt% nanocellulose were prepared by high-shear mixing and applied to wood substrates. The optical, mechanical and chemical properties of cured coatings were characterized. Surface roughness, gloss, scratch resistance, abrasion resistance and resistance against chemicals were determined according to the relevant European standards. Additionally, nanoindentation (NI) was used to assess the micromechanical properties of modified and unmodified coatings. Owing to a higher surface roughness, cellulose-filled coatings showed significantly lower levels of gloss than the unmodified coating indicating that nanocellulose acts as a matting agent. NI experiments revealed a slightly positive effect of nanocellulose addition on the hardness and modulus of the coatings. While scratch resistance improved consistently with increasing nanocellulose addition, abrasion resistance was found to improve only sporadically. Tensile tests on free-standing coating films revealed a significantly higher tensile strength and modulus for cellulose-filled coatings. Overall, the results suggest that the addition of cellulose nanofibres primarily improves the internal cohesion of the coating layer whereby MFC was more effective than NCC.


      PubDate: 2014-12-20T11:29:02Z
       
  • pH-triggered phase inversion and separation of hydrophobised bacterial
           cellulose stabilised Pickering emulsions
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Koon-Yang Lee , Jonny J. Blaker , Jerry Y.Y. Heng , Ryo Murakami , Alexander Bismarck
      The pH-triggered transitional phase behaviour of Pickering emulsions stabilised by hydrophobised bacterial cellulose (BC) is reported in this work. Neat BC was esterified with acetic (C2–), hexanoic (C6–) and dodecanoic (C12–) acids, respectively. We observed that C6– and C12–BC stabilised emulsions exhibited a pH-triggered reversible transitional phase separation. Water-in-toluene emulsions containing of 60vol.% dispersed phase stabilised by C6– and C12–BC were produced at pH 5. Lowering the pH of the aqueous phase to 1 did not affect the emulsion type. Increasing the pH to 14, however, caused the emulsions to phase separate. This phase separation was caused by electrostatic repulsion between modified BC due to dissociable acidic surface groups at high pH, which lowered the surface coverage of the water droplets by modified BC. When the pH was re-adjusted to 1 again, w/o emulsions re-formed for C6– and C12–BC stabilised emulsions. C2–BC stabilised emulsions, on the other hand, underwent an irreversible pH-triggered transitional phase separation and inversion. This difference in phase behaviour between C2–BC and C6–/C12–BC was attributed to the hydrolysis of the ester bonds of C2–BC at high pH. This hypothesis is in good agreement with the measured degree of surface substitution (DSS) of modified BC after the pH-triggered experiments. The DSS of C2–BC decreased by 20% whilst the DSS remained constant for C6– and C12–BC.


      PubDate: 2014-12-20T11:29:02Z
       
  • Nanocomposite films based on cellulose nanofibrils and water-soluble
           polysaccharides
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Jessica Lucenius , Kirsti Parikka , Monika Österberg
      All-polysaccharide composite films were prepared from native, unmodified cellulose nanofibrils (CNF) mixed with various natural water-soluble polysaccharides like carboxymethyl cellulose, galactoglucomannan, xyloglucan and guar gum. Composite films were manufactured by pressurized filtration and hot pressing. The mechanical properties of the films were systematically evaluated in the dry and the wet state. GG was furthermore selectively oxidized using galactose oxidase (EC 1.1.3.9), and the effect of the degree of oxidation on the final composite film properties was shown. It was found that all the tested polysaccharides increased the strength and toughness of the dry composite films at 2 weight percent (wt.%) addition to CNF. After soaking the samples for 24h in water, striking differences between the samples were found: already at 2wt.% CMC the wet strength of the composite films diminished, while the uncharged polysaccharides improved the wet strength. For example, the addition of 2wt.% GGM increased Young’s modulus by a factor of 1.3, the tensile strength by a factor of 2.8, and the toughness by a factor of 3.4. The results are discussed in relation to the amount of water absorbed in the films and possible reasons for the improved properties are suggested.


      PubDate: 2014-12-20T11:29:02Z
       
  • Cellulose nanofibre–poly(lactic acid) microcellular foams exhibiting
           high tensile toughness
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Jana Dlouhá , Lisman Suryanegara , Hiroyuki Yano
      We report here the morphology and tensile properties of polylactic acid–cellulose nanofibre (PLA–CNF) microcellular nanocomposites. Two types of CNF were used for the nanocomposite preparation, native and surface acetylated CNF (ac-CNF). Samples were foamed in a mould to enable tensile testing. The effect of the mould use on the foam morphology was first assessed by comparison with free foamed samples. We found that the mould affected the cell growth stage of the foaming process in neat PLA foam while its effect was less important in nanocomposites. Stiffening and strengthening effect of CNF was greatly enhanced by foaming when compared to their solid counterparts. The most notable change in tensile properties was however the large increase in strain at break resulting in the high tensile toughness of microcellular PLA–CNF nanocomposites. Strain at break increased up to 7.5 times in neat PLA and up to 31.5 times in the foam containing 3% of CNF. Surface acetylation of CNF significantly affected the properties of foams with 9% of CNF loading: while foams with ac-CNF were stiffer, foams with native CNF exhibited higher strain at break and so higher overall toughness.


      PubDate: 2014-12-20T11:29:02Z
       
  • Synthesis of a novel zwitterionic bisphosphonate cyclopolymer containing
           residues of alendronic acid
    • Abstract: Publication date: January 2015
      Source:Reactive and Functional Polymers, Volume 86
      Author(s): Shaikh A. Ali , Hasan A. Al-Muallem , Othman Charles S.O. Al-Hamouz , Mohamad K. Estaitie
      The reaction of 4-(diallylammonio)butanoate, H3PO3 and PCl3 in CH3SO3H created water-insoluble 4-diallylamino-1-hydroxybutylidene-1,1-bisphosphonic acid I, a novel monomer that contained residues of the osteoporosis drug alendronic acid. Monomer (±) I, a zwitterionic tetraprotic acid, in the presence of 2 equivs. NaOH(aq) and the initiator ammonium persulfate, underwent cyclopolymerization to yield water-soluble poly(zwitterion–dianion) (± =) II. Under the influence of pH, II was equilibrated to water-soluble poly(zwitterion–trianion) (± ≡) III, polytetraanion (= =) IV, poly(zwitterion–anion) (± −) V, cationic polyelectrolyte (+) VI and water-insoluble polyzwitterion (±) VII. The solution properties of backbone charges were investigated, and protonation constants of several centers in IV were determined. Polymers that contained residues of alendronic acid should have applications in various fields, including the field of medicine.


      PubDate: 2014-12-20T11:29:02Z
       
  • Selective recovery of a pyridine derivative from an aqueous waste stream
           
    • Abstract: Publication date: January 2015
      Source:Reactive and Functional Polymers, Volume 86
      Author(s): J. Bokhove , T.J. Visser , B. Schuur , A.B. de Haan
      Solvent impregnated resins (SIRs) were evaluated for the recovery of pyridine derivatives from an aqueous waste-stream containing also acetic acid and succinonitrile. For this purpose, a new solvent was developed, synthesized and impregnated in Amberlite XAD4. Sorption studies were used to determine the capacity, selectivity and the mass-transfer rate. A high capacity of 21g 4-cyanopyridine (CP) per kg SIR was found, with very high selectivity toward CP over the other solutes of at least 570. A modified Langmuir equation could describe the equilibrium sorption isotherm. Both the linear driving force model and a Fickian diffusion model were evaluated. The Fick-model described both regeneration and loading best. The CP-diffusivity through the solvent phase was estimated at 6.53·10−13 ±2.5% m2 s−1. The model was validated using fixed-bed column experiments. The R 2 values for this model ranged between 0.94 at a flow rate of 5mL/min and 0.99 at a flow rate of 1mL/min during the loading cycle. Due to mass-transfer limitations the breakthrough profiles were broad and breakthrough occurred after 5 or 23 bed volumes, for flow rates of 5 and 1mL/min, respectively. Both acetic acid and succinonitrile broke through immediately due to the very high CP-selectivity of the SIR.


      PubDate: 2014-12-20T11:29:02Z
       
  • Significance of xylan on the stability and water interactions of
           cellulosic nanofibrils
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Tiia-Maria Tenhunen , Maria Soledad Peresin , Paavo A. Penttilä , Jaakko Pere , Ritva Serimaa , Tekla Tammelin
      In this paper, the significance of xylan on the behaviour of kraft birch pulp based nanofibrillated cellulose (CNF) is discussed. The influence of CNF xylan content on fibril morphology, charge and stability as well as on the film formation ability was investigated, and the features detected on nanoscale and on macroscale are compared. In addition to this, the ability of fibrils to uptake water molecules were investigated by bulk and surface sensitive methods which are dynamic water sorption analysis (DVS) and quartz crystal microbalance with dissipation monitoring (QCM-D) equipped with the humidity module, respectively. Surface xylan plays a significant role as an electrosteric stabilizer in dilute CNF dispersions when the surface forces are dominant whereas the removal of xylan drastically changes the CNF dispersion properties. The settling of the unstable CNF dispersions displays behaviour which is typical for hindered sedimentation. When considering thin nanoscale layers of CNF, nanofibrillated cellulosic materials with high content of surface xylan has somewhat higher ability to bind water molecules. However, it seems that in more concentrated CNF dispersions where the fibrillar network itself plays also a decisive role, especially with respect to film formation ability, the impact of xylan diminishes. Solvent cast macroscale CNF films are still enough dense to maintain good oxygen barrier performance at higher humid conditions although agglomeration tendency of fibrils is higher due to the excessive xylan removal. These findings are of high relevance when considering nanocellulosic materials, especially in the form of gels and films, as templates for high added value material solutions.


      PubDate: 2014-12-20T11:29:02Z
       
  • Tuning the morphology of electroactive polythiophene nano-structures
    • Abstract: Publication date: January 2015
      Source:Reactive and Functional Polymers, Volume 86
      Author(s): Bartlomiej Kolodziejczyk , Orawan Winther-Jensen , Robert Kerr , Paul Firbas , Bjorn Winther-Jensen
      The self-assembly of thiophene monomers and the subsequent oxidative polymerization of them has been studied using the vapour phase polymerization (VPP) platform. A variety of nano-structures were obtained by varying the polymerization conditions with regard to temperature, time, addition of a secondary oxidant and crystal formation in the oxidant layer. The electrochemical and physical characterizations of these nano-structured polythiophene materials were performed using cyclic voltammetry, electron microscopy, UV–vis spectroscopy, conductivity, contact angle and BET surface area measurements. The presence of nano-structures indeed enhances the redox capacity and increases the active surface area compared to the analogue film without nanostructures. The hydrophobicity of the polymeric film is also tuneable from different nano-structures forming on top of the film.


      PubDate: 2014-12-20T11:29:02Z
       
  • Transforming large molecular weight pectin and chitosan into oral protein
           drug nanoparticulate carrier
    • Abstract: Publication date: November 2014
      Source:Reactive and Functional Polymers, Volume 84
      Author(s): Syed Othman Syed Mohamad Al-Azi , Yvonne Tze Fung Tan , Tin Wui Wong
      Polymeric nanoparticle formation is characterized by high risks of premature drug leaching and low drug encapsulation efficiency. This is aggravated by slow nanoparticle formation by large molecular weight polymers due to their slow diffusion kinetics in the reaction medium. This study investigated model protein drug insulin encapsulation by large molecular weight pectin and chitosan. The nanoparticles were prepared through pectin–chitosan coacervation and when necessary, together with pectin or chitosan crosslinking by calcium or tripolyphosphate ions in the same process. The formed particles were nanospray-dried when required. The size, zeta potential, morphology, drug content, drug association efficiency, polymer–polymer and drug-polymer interaction in particulate matrix were examined. The pectin–chitosan nanoparticles were able to encapsulate insulin substantially only if these nanoparticles were formed with rapid particle aggregation into micromatrices as a result of particle surfaces attracting the oppositely charged polymer chains via crosslinking as well as coacervation processes. The particulate aggregation level of micromatrices can be reduced via nanospray drying. Small discrete nanoparticles were obtainable from micromatrices.


      PubDate: 2014-12-20T11:29:02Z
       
  • Synthesis of perylene dianhydride-incorporated main chain polyimides and
           sequential structural transformation through a dipolar cycloaddition
    • Abstract: Publication date: November 2014
      Source:Reactive and Functional Polymers, Volume 84
      Author(s): Mieon Choi , Jung Yun Do
      Perylene dianhydride (PDA)-incorporated polyimides were prepared. The perylene unit in the polyimide was thermally converted to the corresponding N-heterocyclic polyarene unit through a Diels–Alder reaction. The monomer, 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (6FAP), was modified via O-alkylation to improve the solubility of the polymer. 2-Ethylhexyl-attached 6FAP yielded a soluble copolyimide that contained ca. 70mol% PDA using pyromellitic dianhydride. The perylene unit of the copolyimide transformed to a polyarene unit through the dipolar cycloaddition of 4-aryl-1,2,4-triazole-3,5-dione (TAD) and maleic anhydride. The perylene transformation of the polyimide occurred with 50% conversion with maleic anhydride and quantitatively with TAD. The PDA-copolymer exhibited a spectral blue-shift and red-shift by maleic anhydride and TAD, respectively.


      PubDate: 2014-12-20T11:29:02Z
       
  • In situ oxidation-induced gelation of poly(aspartic acid) thiomers
    • Abstract: Publication date: November 2014
      Source:Reactive and Functional Polymers, Volume 84
      Author(s): Benjámin Gyarmati , Enikő Krisch , András Szilágyi
      In situ gelling poly(aspartic acid) thiomers are investigated to demonstrate their potential application in the development of injectable formulations. The chemical stability of the thiomer solutions is measured against air to determine the maximum storage time of the solution before injection. Hydrogels exhibit considerably large storage moduli after the chemical oxidation of the low-viscosity thiomer solution. The gelation time can be controlled within 2–6min, which is advantageous for injection because the thiomer solution and the oxidising agent can be mixed safely in a two-chamber system before injection into the desired site of the body.
      Graphical abstract image

      PubDate: 2014-12-20T11:29:02Z
       
  • The effect of cellulose nanowhiskers on the flexural properties of
           self-reinforced polylactic acid composites
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Kazi M. Zakir Hossain , Reda M. Felfel , Chris D. Rudd , Wim Thielemans , Ifty Ahmed
      Self-reinforced polylactic acid (SR PLA) composites incorporating cellulose nanowhiskers (CNWs) were produced by coating orientated PLA fibres with a polyvinyl acetate (PVAc)–CNW mixture as a binder prior to hot compaction at 95°C. PLA fibres were produced with an average diameter of 11 (±0.9) μm via a melt-drawing process at 180°C. Scanning electron microscopy (SEM) images revealed that the CNWs imparted roughness to the PLA fibre surface. Cross-sectional examination of the SR PLA composites after hot-pressing confirmed that the PLA fibres had maintained their morphology. Incorporation of 8wt% CNWs within the SR-PLA composites revealed an increase in their flexural strength (48%) and modulus (39%) compared to the control composite (flexural strength ∼82MPa and modulus ∼3.9GPa). In addition, whilst the control SR-PLA composite revealed quite brittle characteristics, the addition of CNWs and PVAc gave the self-reinforced composite a more ductile behaviour.
      Graphical abstract image

      PubDate: 2014-12-20T11:29:02Z
       
  • Aligned unidirectional PLA/bacterial cellulose nanocomposite fibre
           reinforced PDLLA composites
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Jonny J. Blaker , Koon-Yang Lee , Matthew Walters , Marc Drouet , Alexander Bismarck
      In an effort to enhance the properties of polylactide (PLA), we have developed melt-spinning techniques to produce both PLA/nanocellulose composite fibres, and a method akin to layered filament winding followed by compression moulding to produce self-reinforced PLA/nanocellulose composites. Poly(L-lactide) (PLLA) fibres were filled with 2wt.% neat and modified bacterial cellulose (BC) in an effort to improve the tensile properties over neat PLA fibres. BC increased the viscosity of the polymer melt and reduced the draw-ratio of the fibres, resulting in increased fibre diameters. Nonetheless, strain induced chain orientation due to melt spinning led to PLLA fibres with enhanced tensile modulus (6GPa) and strength (127MPa), over monolithic PLLA, previously measured at 1.3GPa and 61MPa, respectively. The presence of BC also enhanced the nucleation and growth of crystals in PLA. We further produced PLA fibres with 7wt.% cellulose nanocrystals (CNCs), which is higher than the percolation threshold (equivalent to 6vol.%). These fibres were spun in multiple, alternating controlled layers onto spools, and subsequently compression moulded to produce unidirectional self-reinforced PLA composites consisting of 60vol.% PLLA fibres reinforced with 7wt.% CNC in a matrix of amorphous PDLLA, which itself contained 7wt.% of CNC. We observed improvements in viscoelastic properties of up to 175% in terms of storage moduli in bending. Furthermore, strains to failure for PLLA fibre reinforced PDLLA were recorded at 17%.


      PubDate: 2014-12-20T11:29:02Z
       
  • Reinforcing efficiency of nanocellulose in polymers
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Yvonne Aitomäki , Kristiina Oksman
      Nanocellulose extracted from renewable sources, is a promising reinforcement for many polymers and is a material where strong interfibre hydrogen bonds add effects not seen in microfiber composites. Presented is a tool for comparing different nanocellulose composites based on estimating the efficiency of nanocellulose reinforcement. A reinforcing efficiency factor is calculated from reported values of elastic modulus and strength from various nanocellulose composites using established micromechanical models. In addition, for the strength, a network model is derived based on fibre–fibre bond strength within nanocellulose networks. The strength results highlight the importance of the plastic deformation in the nanocellulose composites. Both modulus and strength efficiency show that the network strength and modulus has a greater effect than that of the individual constituents. In the best cases, nanocellulose reinforcement exceeds all model predictions.


      PubDate: 2014-12-20T11:29:02Z
       
  • The non-trivial role of native xylans on the preparation of TEMPO-oxidized
           cellulose nanofibrils
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Qijun Meng , Hailong Li , Shiyu Fu , Lucian A. Lucia
      Cellulose nanofibrils have become increasingly prized as a raw material toward the preparation of composites due to their specific surface character and biocompatibility. TEMPO-mediated oxidation with post-mechanical treatment has been proposed as a promising method for the preparation of cellulose nanofibrils from cellulosic raw materials. In the current study it was found that the native hemicellulosic components in the raw material played a pivotal chemical role on the kinetics of generation of TEMPO-oxidized cellulose nanofibrils (TOCNs), as well as on thermal stability, and transmittance. The removal of xylans from the original feedstock facilitated not only an increase in both the carboxylate content and water retention value of the TEMPO-oxidized fibers, but also improved the transmittance of subsequently obtained TOCNs suspensions. It was also determined that the presence of xylans in the cellulosic feedstock hindered chemical accessibility through a barrier mechanism in which the TEMPO-mediated oxidation reaction rate was reduced.


      PubDate: 2014-12-20T11:29:02Z
       
  • Influence of mechanical treatments on the properties of cellulose
           nanofibers isolated from microcrystalline cellulose
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Davide Bandera , Janak Sapkota , Sébastien Josset , Christoph Weder , Philippe Tingaut , Xin Gao , E. Johan Foster , Tanja Zimmermann
      The possibility of preparing cellulose whiskers-like materials by mechanical treatment of commercially available microcrystalline cellulose (MCC) was explored. High shear homogenization, grinding with a supermass colloider, and hammer-milling were the processes selected to disintegrate the MCC, which yielded F-MCC, G-MCC and H-MCC, respectively. Processing aqueous dispersions with high solid content allowed for the production of cellulose particles with greatly reduced dimensions. Morphological characterization revealed that homogenization and grinding reduced the particle size more effectively than hammer-milling, although the disintegration was incomplete in all cases. The reinforcing potential of the materials was evaluated against commercially available whiskers by using the various particles as fillers to mechanically reinforce hydroxypropylcellulose. Nanocomposite films containing 5, 10, or 20wt.% of the filler were prepared and the mechanical properties were characterized. The results show that H-MCCs are just slightly better than the original MCC, whereas F-MCC and G-MCC performed similar to whiskers at 10wt.% loading, despite the presence of a fraction of micrometer-sized particles. It is therefore reasonable to envision the use of the more easily produced F-MCC and G-MCC as replacement of cellulose whiskers in some applications.


      PubDate: 2014-12-20T11:29:02Z
       
  • Using gelatin protein to facilitate paper thermoformability
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Alexey Khakalo , Ilari Filpponen , Leena-Sisko Johansson , Alexey Vishtal , Arcot R. Lokanathan , Orlando J. Rojas , Janne Laine
      One of the main challenges of fiber-based packaging materials is the relatively poor elongation of cellulose under stress, which limits formability and molding in related products. Therefore, in this investigation we first used cellulose thin films and surface sensitive tools such as quartz crystal microbalance (QCM-D), surface plasmon resonance (SPR) and X-ray photoelectron spectroscopy (XPS) to evaluate the cellulose–gelatin interactions. It was found that the highest adsorption of gelatin onto cellulose occurred at the isoelectric pH of the protein. Based on this and other results, a gelatin loading is proposed to facilitate molecular and surface interactions and, thus to improve the formability of cellulose-based materials in paper molding. Aqueous gelatin solutions were sprayed on the surface of wet webs composed of softwood fibers and the chemical and mechanical changes that occurred were quantified. Upon gelatin treatment the elongation and tensile strength of paper under unrestrained drying was increased by ∼50% (from ∼10% to 14%) and by ∼30% (from 59 to 78Nm/g), respectively. The mechanical performance of gelatin-treated fibers was further improved by glutaraldehyde-assisted cross-linking. The proposed approach represents an inexpensive and facile method to improve the plasticity of fiber networks, which otherwise cannot be processed in the production of packaging materials by direct thermoforming.


      PubDate: 2014-12-20T11:29:02Z
       
  • TEMPO-oxidized cellulose nanofibrils prepared from various plant
           holocelluloses
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Ryota Kuramae , Tsuguyuki Saito , Akira Isogai
      Plant holocelluloses were prepared from softwood, gymnosperm, hardwood, and herbaceous species, and subjected to TEMPO-mediated oxidation using the TEMPO/NaBr/NaOCl and TEMPO/NaOCl/NaO2Cl systems in water at pH 10 and 6.8, respectively. Weight recovery ratios of the water-insoluble TEMPO-oxidized holocellulose (TOH) fractions and their carboxylate contents, sugar compositions, and X-ray diffraction patterns were measured. When the oxidation at pH 10 was used, the carboxylate content of the TOHs increased up to 1.4–1.7mmolg− 1. The oxidation at pH 6.8 resulted in higher weight recovery ratios of TOHs and their lower carboxylate contents (0.8–1.2mmolg− 1) than those prepared by the oxidation at pH 10. Hemicelluloses in plant holocelluloses are preferentially degraded to water-soluble fractions and removed from TOHs in the oxidation at pH 10. In contrast, the TEMPO-mediated oxidation at pH 6.8 provides hemicellulose-rich TOHs in high weight recovery ratios, although their nanofibrillation yields were low. All TEMPO-oxidized holocellulose nanofibrils (TOHNs) obtained by mechanical disintegration treatment of TOHs in water had the same average widths of ∼3nm, when measured by atomic force microscopy in water, which were consistent with those of TOHs determined from X-ray diffraction patterns. The number-average lengths of TOHNs were 500–600nm.
      Graphical abstract image Highlights

      PubDate: 2014-12-20T11:29:02Z
       
  • Synthesis and characterization of chitosan hydrogels cross-linked with
           dicarboxylic acids
    • Abstract: Publication date: November 2014
      Source:Reactive and Functional Polymers, Volume 84
      Author(s): N.E. Valderruten , J.D. Valverde , F. Zuluaga , E. Ruiz-Durántez
      Chitosan hydrogels cross-linked with dicarboxylic acids were prepared. Succinic, glutaric and adipic acid were used as cross-linking agents, the goal being to compare the effect of the length of the chain on the behavior of the material obtained. The swelling properties were studied at different pHs and temperatures, and it was discovered that these properties depend particularly on the pH of the environment. Creep-recovery and stress-relaxation studies were performed to determine mechanical properties and the chitosan/succinic acid hydrogels exhibited a completely viscous behavior. Thermal studies were carried out using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC results revealed that the materials obtained are completely amorphous. Acetaminophen was used as a positive control for the release kinetics studies. Upon fitting the results to a specific mathematical model, it was determined that the release process is controlled by diffusion and relaxation of the polymer network.


      PubDate: 2014-12-20T11:29:02Z
       
  • Surface maleylation and naphthaloylation of chitin nanofibers for property
           enhancement
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): S. Ifuku , N. Suzuki , H. Izawa , M. Morimoto , H. Saimoto
      Surface N-maleylation and N-naphthaloylation of chitin nanofiber (NF) were achieved by reaction with maleic and naphthalic anhydrides in water, respectively. Maleyl and naphthaloyl groups were sufficiently introduced to an amino group on a surface-deacetylated chitin NF. The characteristic nanofiber morphology was maintained after maleylation and naphthaloylation. These NFs were homogeneously dispersed in several organic solvents. Especially, naphthaloyl chitin NF was dispersed even in aromatic solvents, owing to the high level of solvation interactions with the naphthaloyl group. The NF dispersions in those aromatic solvents exhibited a dispersive-to-precipitate transition response at approximately 29°C. Moreover, the naphthaloyl chitin NF dispersion cut harmful ultraviolet light. The maleyl chitin NF formed a self-standing gel after cross-linking polymerization.


      PubDate: 2014-12-20T11:29:02Z
       
  • Preparation and application of starch nanoparticles for nanocomposites: A
           review
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Déborah Le Corre , Hélène Angellier-Coussy
      The increasing scientific and industrial interest for starch nanoparticles (SNP) has led to the development of numerous methods for preparing sub-micron starch fillers for nanocomposites applications. Starch nanocrystals (SNC), which constitute the focus of this review, are one type of SNP with crystalline property and platelet like morphology. SNC can be extracted from various starch botanical sources, allowing to obtain a large range of amylose content, shape, viscosity in suspension, surface reactivity and thermal resistance. To date, the most common method for extracting SNC remains the mild acid hydrolysis of the amorphous parts of native granular starch. So far, alternative methods render much lower yield. Since first publications on SNC, the principal aim is to use them as reinforcement in polymer matrices. Thanks to the reactive nature of starch, SNC surface can be modified by grafting or cross-linking which renders them more readily dispersible in the polymer matrix. The present review focus on the reinforcing effect and mechanisms of SNC, as well as on their impact of barrier properties of polymers.


      PubDate: 2014-12-20T11:29:02Z
       
  • A review on lignin-based polymeric, micro- and nano-structured materials
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Antoine Duval , Martin Lawoko
      Next to cellulose, lignin is the second most abundant biopolymer, and the main source of aromatic structures on earth. It is a phenolic macromolecule, with a complex structure which considerably varies depending on the plant species and the isolation process. Lignin has long been obtained as a by-product of cellulose in the paper pulp production, but had rather low added-value applications. Changes in the paper market have however stimulated the need to focus on other applications for lignins. In addition, the emergence of biorefinery projects to develop biofuels, bio-based materials and chemicals from carbohydrate polymers should also generate large amounts of lignin with the potential for value addition. These developments have brought about renewed interest in the last decade for lignin and its potential use in polymer materials. This review covers both the topics of the direct use of lignin in polymer applications, and of the chemical modifications of lignin, in a polymer chemistry perspective. The future trend toward micro- and nanostructured lignin-based materials is then addressed.


      PubDate: 2014-12-20T11:29:02Z
       
  • Temperature- and pH-sensitive membrane formed from blends of
           poly(vinylidene fluoride)-graft-poly(N-isopropylacrylamide) and
           poly(acrylic acid) microgels
    • Abstract: Publication date: November 2014
      Source:Reactive and Functional Polymers, Volume 84
      Author(s): Xi Chen , Bowu Zhao , Peng Han , Weigui Fu , Li Chen
      Temperature- and pH-responsive membranes prepared from blends of poly(vinylidene fluoride)-graft-poly(N-isopropylacrylamide)(PVDF-g-PNIPAM) copolymer and poly(acrylic acid) (PAA) microgels in N,N-dimethylformamide (DMF) solution by phase inversion method. PAA microgels help PNIPAM chains largely enrich onto membrane surface. Furthermore, adding PAA microgels increases the porous size, porosity and hydrophilic property of the blend membrane. The membranes show temperature-sensitivity between 30 and 35°C, and pH-sensitivity between pH 3 and 5 on permeating aqueous solutions. Meanwhile, the blend membranes keep good antifouling property even if one of the hydrophilic components becoming hydrophobic in response to temperature or pH stimuli, which is superior to single-sensitive PVDF membrane.


      PubDate: 2014-12-20T11:29:02Z
       
  • Editors and Editorial Board
    • Abstract: Publication date: November 2014
      Source:Reactive and Functional Polymers, Volume 84




      PubDate: 2014-12-20T11:29:02Z
       
  • Poly(NIPAAm-co-β-cyclodextrin) microgels with drug hosting and
           temperature-dependent delivery properties
    • Abstract: Publication date: November 2014
      Source:Reactive and Functional Polymers, Volume 84
      Author(s): Marieta Constantin , Sanda Bucatariu , Paolo Ascenzi , Bogdan C. Simionescu , Gheorghe Fundueanu
      One of the most important drawbacks of the thermosensitive hydrogels based on N-isopropylacrylamide (NIPAAm) is the lack of functional groups able to specifically bind drugs; moreover, these hydrogels are not biodegradable. In order to overcome these inconveniences, poly(NIPAAm-co-β-cyclodextrin) (poly(NIPAAm-co-β-CD)) microgels were obtained by cross-linking polymerization of the corresponding monomers. β-CD was first functionalized with an appropriate amount of vinyl groups, thus acting both as a co-monomer with hosting properties and as a biodegradable cross-linker. The volume phase transition temperature (VPTT) of the microgels was determined under simulated physiological conditions by measuring the swelling degree and by microcalorimetry. The microgels, due to their small size and high porosity, possess a relative rapid swelling/deswelling rate around the human body temperature. The hydrogels were loaded with the model drug diclofenac by inclusion within cyclodextrin cavity and the release studies were performed under simulated physiological conditions, below and the above the VPTT. In the presence of α-amylase (from Aspergillus Oryzae), microgels have showed a low degradation rate (15% of initial weight after 7days), the erosion occurring especially at the surface.


      PubDate: 2014-12-20T11:29:02Z
       
  • Alternate and random (co)polymers composed of anthracene and
           chloromethylstyrene units through controlled radical ring-opening
           
    • Abstract: Publication date: January 2015
      Source:Reactive and Functional Polymers, Volume 86
      Author(s): Kazuhiro Nakabayashi , Ayumi Tsuda , Hiroshi Otani , Hideharu Mori
      A cyclic monomer containing the chloromethyl unit 10-methylene-9,10-dihydroanthryl-9-spiro(4′-chloromethylphenyl)cyclopropane (MDCMS) was polymerized using a controlled radical ring-opening polymerization via a reversible addition-fragmentation chain transfer (RAFT) process to afford a nonconjugated alternate polymer composed of anthracene and chloromethylstyrene (CMS) units. Well-defined random copolymers were obtained through the ring-opening RAFT copolymerization. Various functional groups were incorporated into the alternate polymer. The alternate polymer containing imidazole rings exhibited fluorescence quenching as a result of charge transfer. Fluorescence resonance energy transfer (FRET) was observed in the alternate polymers containing naphthalene and thiophene rings. The random copolymers obtained by copolymerization followed by post-functionalizations exhibited characteristic optoelectronic properties that differed from those of the alternate polymers.


      PubDate: 2014-12-20T11:29:02Z
       
  • Functionalized electrospun regenerated cellulose fibers for immobilizing
           pyranose 2-oxidase
    • Abstract: Publication date: January 2015
      Source:Reactive and Functional Polymers, Volume 86
      Author(s): Weerapha Panatdasirisuk , Thammasit Vongsetskul , Jeerus Sucharitakul , Pimchai Chaiyen , Pramuan Tangboriboonrat
      This work aims to reuse pyranose 2-oxidase (P2O) and improve its thermal stability compared to the wild-type enzyme by immobilizing onto regenerated cellulose fibers (RC). The P2O-immobilized RC fibers (P2O-RC) showed the improvement in terms of thermal stability. Cellulose acetate (CA) fibers (229±42nm) were electrospun from 17% w/w CA (MW ∼3×104 g/mol) with 5% w/w Tween 80 dissolved in a mixture of water (25% w/w) and acetic acid (75% w/w) at an applied voltage of 25kV and a fiber collection distance of 10cm. Then, the fiber surface was treated with 0.5M potassium hydroxide in ethanol and 12% w/v glutaraldehyde using aluminum sulfate hexadecahydrate as a catalyst before P2O was immobilized on the treated fibers. Effects of the immobilization process on thermal and pH stability of P2O were investigated by measuring P2O activity based on peroxidase coupled assay. Results indicated that P2O-RC catalyzed the oxidation of glucose at high temperatures (60 and 70°C) better than the free enzyme did. Therefore, P2O-RC are potentially useful as a heterogeneous catalyst under the conditions that P2O cannot endure.


      PubDate: 2014-12-20T11:29:02Z
       
  • Installation of a reactive site for covalent wiring onto an intrinsically
           conductive poly(ionic liquid)
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Scott M. Brombosz , Sungwon Lee , Millicent A. Firestone
      Post-polymerization radical bromination of a nanostructured poly(ionic liquid) that selectively introduces a reactive bromo-group onto the polyalkylthiophene backbone is described. Raman and FT-IR spectroscopy proves that the bromine is successfully introduced at the 3-methyl position of the thiophene and that the molecular structure of the polymer remains largely intact with only minimal chain scission detected. FT-IR and Vis-NIR spectroscopy indicates that incorporation of the bromine induces twisting (loss of co-planarity) of the polythiophene backbone. WAXS confirms retention of an ordered lamellar structure with minor lattice spacing contraction. Cyclic voltammetry confirms spectroscopic findings that the bromination reaction yields a stable p-doped polymer. The installed bromine is susceptible to nucleophilic displacement permitting the covalent attachment of other functional molecules, such as a dialkylphosphonate. Elemental analysis of such a transformation established that 100% functionalization can be achieved. These results collectively demonstrate that post-modification of a π-conjugated polymer can be used to both tune electronic and photonic properties, as well as install a chemoselective attachment point for the covalent wiring of other molecules.
      Graphical abstract image

      PubDate: 2014-12-20T11:29:02Z
       
  • Cellulose nanopapers as tight aqueous ultra-filtration membranes
    • Abstract: Publication date: Available online 11 October 2014
      Source:Reactive and Functional Polymers
      Author(s): Andreas Mautner , Koon-Yang Lee , Tekla Tammelin , Aji P. Mathew , Alisyn J. Nedoma , Kang Li , Alexander Bismarck
      Recently, we have demonstrated the use of wood-derived nanocellulose papers, herein termed nanopapers, for organic solvent nanofiltration applications. In this study, we extend the use of these nanopapers to tight ultrafiltration (UF) membranes. The feasibility of such nanopaper-based UF membranes intended for use in water purification is shown. Four types of nanocelluloses, namely bacterial cellulose, wood-derived nanocellulose, TEMPO-oxidized cellulose nanofibrils and cellulose nanocrystals, were used as raw materials for the production of these nanopaper-based membranes. The resulting nanopapers exhibit a transmembrane permeance in the range of commercially available tight UF membranes with molecular weight cut-offs ranging from 6 to 25kDa, which depends on the type of nanocellulose used. These molecular weight cut-offs correspond to average pore sizes of a few nanometres. The rejection performance of the nanopapers is on the border of nanofiltration and UF. We demonstrate that the pore size of the nanopapers can be controlled by using different types of nanocellulose fibrils.


      PubDate: 2014-12-20T11:29:02Z
       
  • Polymer-based chelating adsorbents for the selective removal of boron from
           water and wastewater: A review
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Mohamed Mahmoud Nasef , Madana Nallappan , Zaini Ujang
      Boron removal from water is a highly interesting research area that has been addressed in various investigations in the recent years. This is due to the expansion of harmful effects of boron traces in water streams on the environment and human health with the rise in boron global demand in various industries that coincided with the implantation of more stringent water quality standards. Various technologies have been applied for the removal of boron from water solutions, including ion exchange technology, which has a great potential in treating varieties of boron-containing streams up to levels in parts per million using boron-selective adsorbents. This article comprehensively reviews the latest progress in the development of polymer-based boron-selective (chelating) materials and their applications for the removal of boron from water solutions, including commercial boron-selective resins (BSRs) and their researched counterparts. The emerging trends in the development of alternative adsorbents with different substrates, morphologies, and functional groups are also elucidated. The future directions to overcome the limitations of the present generation of resins are also discussed.


      PubDate: 2014-12-20T11:29:02Z
       
  • Preparation and characterization of polymeric ligand exchanger based on
           chitosan hydrogel for selective removal of phosphate
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Byungryul An , Ka-Young Jung , Dongye Zhao , Sang-Hyup Lee , Jae-Woo Choi
      Polymeric ligand exchangers (PLEs) are typically prepared using commercial chelating resins which are often costly and less “green”. In this work, we prepared a new PLE by immobilizing Cu(II) on a low-cost, natural biopolymer chitosan. It was confirmed that the Cu2+ ions were bonded to chitosan by complexing with the nitrogen and hydroxyl groups in the chitosan polymer chain, leading to a reduction in the size of the hydrogel and intensified density of the biopolymer. The chelating interaction between nitrogen and Cu2+ acts as a crosslinker that improves the physical and chemical stability of the PLE. The pH sorption tests confirmed a pK a of ∼7.0 for the biopolymer. The PLE reverses the affinity sequence of standard anionic resins, and displayed much greater affinity toward strong ligands such as phosphate than sulfate due to concurrent electrostatic and Lewis acid-base interactions between immobilized Cu2+ ions and phosphate regardless of solution pH. The maximum phosphate uptake was estimated to be 70mgg−1 and 35mgg−1 in single and binary-component systems, respectively. Fixed-bed column tests revealed that the PLE may be used for selective removal of phosphate of strong ligand characteristics over sulfate.


      PubDate: 2014-12-20T11:29:02Z
       
  • Impact of preparation method on physical properties and gas separation
           performance of fluorinated copolymer membranes
    • Abstract: Publication date: Available online 22 October 2014
      Source:Reactive and Functional Polymers
      Author(s): Soon-Chien Lu , Ivo F.J. Vankelecom
      Two batches of poly(vinylidene fluoride–hexafluoropropylene) [P(VDF–HFP)] copolymer with different monomer ratios were thoroughly characterised and cast into membranes to relate the fundamental properties of this copolymer with its performance in CO2 separation. Solubility testing revealed that the PVDF part of the copolymer was dominating and calculations with Hansen’s solubility parameters corroborated the outcome. A very slow solvent evaporation rate and use of solvents with a high boiling point were found to be essential in the formation of defect-free membranes from this copolymer for gas separations. Physical examination, DSC, XRD and TGA were also performed to better link the fundamental membrane properties to the gas separation performance. A low crystallinity in the prepared P(VDF–HFP) membranes was favourable in terms of compatibility, solubility, membrane formation and CO2 separations.


      PubDate: 2014-12-20T11:29:02Z
       
  • Biodegradable hybrid poly(3-hydroxyalkanoate)s networks through
           silsesquioxane domains formed by efficient UV-curing
    • Abstract: Publication date: November 2014
      Source:Reactive and Functional Polymers, Volume 84
      Author(s): C. Lorenzini , D.L. Versace , J. Babinot , E. Renard , V. Langlois
      New bridged silsesquioxanes derived from poly(3-hydroxyalkanoate)s were synthesized, according to the sol–gel process, by conventional acidic, basic hydrolysis or by UV-curing in presence of cationic photo-initiator to compare the properties of the resulting networks. First, microwave assisted alcoholysis in the presence of ethylene glycol provided an efficient method for engineering PHA-diols. These well-defined oligoesters have been derivatized into telechelic bis-triethoxysilyl precursors and sol gel chemistry was employed as cross-linking reaction method. The thermal stability of PHA was improved by incorporation into the silica network, except in basic condition, due to simultaneous formation of the network and the degradation of the PHA backbone. The glass-transition temperatures of the networks prepared in acidic conditions increased from −14°C up to +16°C. 29Si NMR measurements also showed that UV curing catalyzed by cationic photo-initiator promotes a high degree of condensation in the organic network that became totally amorphous. This method is a straightforward way applied at room temperature in a very short reaction time (i.e., 300s) to obtain crosslinked network that remain partially biodegradable by lipase.


      PubDate: 2014-12-20T11:29:02Z
       
  • Synthesis and characterization of poly(tetramethylsilarylenesiloxane)
           derivatives bearing benzodithiophene moieties
    • Abstract: Publication date: November 2014
      Source:Reactive and Functional Polymers, Volume 84
      Author(s): Hitoshi Hanamura , Ryoichi Hattori , Ryo Maruyama , Nobukatsu Nemoto
      Poly(tetramethylsilarylenesiloxane) derivatives bearing benzo[1,2-b;4,5-b′]dithiophene (P1) and benzo[2,1-b;3,4-b′]dithiophene (P2) moieties were prepared via polycondensation of the corresponding disilanol monomers, that is, 2,6-bis(dimethylhydroxysilyl)benzo[1,2-b;4,5-b′]dithiophene (M1) and 2,7-bis(dimethylhydroxysilyl)benzo[2,1-b;3,4-b′]dithiophene (M2), respectively. It was deduced that P1 is a crystalline polymer while P2 is an amorphous one from the results of differential scanning calorimetry (DSC). Bathochromic and hyperchromic effects were observed in the absorption and fluorescence spectra when dimethylsilyl substituents were introduced on the benzo[1,2-b;4,5-b′]dithiophene and benzo[2,1-b;3,4-b′]dithiophene skeletons. The fluorescence quantum yields (Φ Fs) were not improved by the introduction of dimethylsilyl groups onto the benzo[1,2-b;4,5-b′]dithiophene and benzo[2,1-b;3,4-b′]dithiophene skeletons, whereas the improvement in the Φ Fs was remarkable in the case of poly(tetramethylsilarylenesiloxane) derivatives that possessed the corresponding fused benzene ring systems, i.e., poly(tetramethyl-2,6-silanthrylenesiloxane) and poly(tetramethyl-1,8-silphenanthrylenesiloxane).


      PubDate: 2014-12-20T11:29:02Z
       
  • Editors and Editorial Board
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85




      PubDate: 2014-12-20T11:29:02Z
       
  • Renewable nanomaterials, polymers and composites
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Lars Berglund , Alexander Bismarck , Alain Dufresne , Akira Isogai



      PubDate: 2014-12-20T11:29:02Z
       
  • Synthesis and antimicrobial activities of polysiloxane-containing
           quaternary ammonium salts on bacteria and phytopathogenic fungi
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Yaling Lin , Qiongqiong Liu , Liujun Cheng , Yufeng Lei , Anqiang Zhang
      A series of dimethylaminopropyl benzyl chloride grafted polysiloxanes (PDMS-g-BCs) with tunable molecular weights and cationic content were synthesized, and the effect of polymer structure on the antimicrobial activities against bacteria (Escherichia coli (E. coli) and Staphylococcus albus (S. albus)) and phytopathogenic fungi (Rhizoctonia solani (R. solani) and Fusarium oxysporum f. sp. cubense race 4 (Foc4)) were systematically assessed. The antibacterial activity was evaluated by determining the minimum inhibitory concentration (MIC) against E. coli and S. albus by the broth dilution method, and the antifungal activity was measured by mycelia growth inhibition as well as by the MIC and minimum fungicidal concentration (MFC) values. The molecular weight and cationic content were major determinants of the activities of PDMS-g-BCs; when the molecular weight was approximately 2500g/mol and the cationic content was approximately 20mol% of the total siloxane units, PDMS-g-BCs gained strong antimicrobial activities toward both E. coli and Foc4, comparable to those of a commonly used broad-spectrum microbicide benzalkonium chloride, making PDMS-g-BCs promising fungicidal agents for plant disease control.


      PubDate: 2014-12-20T11:29:02Z
       
  • Photoreversible crosslinking of poly-(ethylene-butyl-acrylate) copolymers
           functionalized with coumarin chromophores using microwave methodology
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): L. López-Vilanova , I. Martinez , T. Corrales , F. Catalina
      Coumarin chromophores were successfully bonded onto ethylene-co-butyl acrylate (EBA) with a butyl ester content of 17% under mild conditions in solution via microwave irradiation. The synthesis consisted of three steps: partial conversion of butyl esters into carboxylic acid groups, conversion of carboxylic acid functionalities into acid chloride groups and esterification using 7-(3-hydroxy-propoxy) coumarin. The EBA modified with coumarin groups was characterized using FTIR, NMR, UV spectroscopy and thermal methods. The EBA modified with coumarin moieties (EBA-g-coum) was crosslinked by irradiating at 365nm, and the coumarin photodimers were cleaved by irradiating at 280nm. The reversibility of the photoreactions in the solid state was monitored using UV spectroscopy. Additionally, the mechanical properties of the materials were determined.


      PubDate: 2014-12-20T11:29:02Z
       
  • Macroporous polymers tailored as supports for large biomolecules: Ionic
           liquids as porogenic solvents and as surface modifiers
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Diana Flor Izquierdo , Malcolm Yates , Pedro Lozano , M. Isabel Burguete , Eduardo García-Verdugo , S.V. Luis
      Highly ordered rod-like polymeric monoliths with large-pores have been successfully synthesized using ionic liquids (ILs) IL-1 (1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIM][NTf2]) and IL-2 (1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [OMIM][NTf2]) as alternative porogenic solvents. The presence of ILs can not only promote the formation of a highly ordered macroporous structure, control the morphology of the polymer and control the chemical composition of surfaces for monoliths prepared from DVB. In this regard, post-functionalization of the monoliths can be easily achieved using the functional monomers introduced in the polymerization process or the unreacted vinyl groups present in the polymeric matrix. This control has allowed the preparation of monolithic Supported Ionic Liquid-like Phases (m-SILLPs) with excellent morphological properties. These m-SILLPs have been studied as supports for large biomolecules. Bioadsorption studies show that the adsorbed amount of protein reaches values as high as 150–200mg of protein per gram of support.


      PubDate: 2014-12-20T11:29:02Z
       
  • Biopolymeric matrices made of carrageenan and corn starch for the
           antioxidant extracts delivery of Cuban red propolis and yerba mate
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Liliam Chang-Bravo , Alex López-Córdoba , Miriam Martino
      The design of biopolymeric matrices for the delivery of bioactive compounds constitutes a useful strategy to prevent the spoilage of food products. In the current work, carrageenan–starch films with antioxidant extracts of Cuban red propolis and yerba mate were prepared by casting. The morphological analysis by SEM showed a more homogeneous structure for the yerba mate films in comparison with the propolis ones. The incorporation of the natural extracts affected the dynamic-mechanical behavior of the films, whereas their crystallinity degrees were maintained. FTIR analysis showed stronger interactions of the polymer matrix with the propolis extract than with the yerba mate one. The films exhibited differences in their mechanical properties; higher tensile strength values were obtained for the yerba mate films than for the propolis samples. However, the last films exhibited higher elongation at break. Both matrices showed good stability of the active compounds along 6months of storage at 75% RH and 23°C. After this time, the samples showed an increase in their DPPH scavenging activity. The release behavior of the phenolic compounds from the films in an aqueous medium was assayed finding significant differences (p <0.05) between release rates of both extracts.


      PubDate: 2014-12-20T11:29:02Z
       
  • Reactive phase inversion for manufacture of asymmetric poly (ether imide
           sulfone) membranes
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Taghreed A. Jalal , Iran D. Charry Prada , Russel Tayouo , Emmanuel P. Giannelis , Suzana P. Nunes
      Poly (ether imide sulfone) membranes were manufactured by combining phase inversion and functionalization reaction between epoxy groups and amine modified polyether oligomers (Jeffamine) or TiO2 nanoparticles. Polysilsesquioxanes containing epoxy functionalities were in-situ grown in the casting solution and made available for further reaction with amines in the coagulation/annealing baths. The membranes were characterized by field emission scanning electron microscopy, porosimetry and water flux measurements. Water permeances up to 1500lm−2 h−1 bar−1 were obtained with sharp pore size distribution and a pore diameter peak at 66nm, confirmed by porosimetry, which allowed 99.2% rejection of γ-globulin. Water flux recovery of 77.5% was achieved after filtration with proteins. The membranes were stable in 50:50 dimethylformamide/water, 50:50 N-methyl pyrrolidone/water and 100% tetrahydrofuran. The possibility of using similar concept for homogeneous and stable attachment of nanoparticles on the membrane surface was demonstrated.


      PubDate: 2014-12-20T11:29:02Z
       
  • Catalytic graphitization of electrospun cellulose nanofibres using silica
           nanoparticles
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Libo Deng , Anna E. Lewandowska , Robert J. Young , Guoping Zhang , Rong Sun , Stephen J. Eichhorn
      Electrospun cellulose nanofibres have been graphitized in the presence of silica (SiO2) nanoparticles. The structure of the resultant SiC/C hybrids was characterised using transmission electron microscopy, X-ray diffraction and Raman spectroscopy. Bamboo-like silicon carbide (SiC) nanostructures were observed emanating from the nanofibres treated at 1500°C which were thought to grow through a vapour–liquid–solid process. The formation of SiC was also thought to lead to a higher degree of graphitization for the electrospun cellulose fibres. These porous and graphitized nanofibres might find applications in electrochemical energy storage.


      PubDate: 2014-12-20T11:29:02Z
       
  • A preliminary assay of the potential of soy protein isolate and its
           hydrolysates to provide interfiber bonding enhancements in lignocellulosic
           furnishes
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Abdus Salam , Lucian A. Lucia , Hasan Jameel
      Soy protein isolate (SPI) was extracted from soy flour and hydrolyzed with hydrochloric acid, sodium hydroxide, and enzyme, separately, to provide a series of hydrolysates. The SPI and its hydrolysis products were later cross-linked with ethylendiaminetetraacetic acid (EDTA) in the presence of sodium hypophosphite (SPH) after which they were complexed to chitosan as part of an on-going general chemical strategy in our laboratories to improve their incorporation into old corrugated container (OCC) matrix and thus increase inter-fiber bonding. Approximately 2% SPI-EDTA-chitosan and hydrolyzed SPI-EDTA-chitosan additives by mass (OCC-based slurry) were thoroughly mixed before generating a sheet for physical testing. The tensile and burst indices of the SPI-EDTA-chitosan additive-treated OCC pulp sheet increased 46.3% and 61.85%, respectively, while the inter fiber bonding of SPI-EDTA-chitosan additive-treated OCC pulp sheet increased 74.86% compared to the control, albeit having a decreased tear strength and roughness, with significantly increased gloss. The additive-treated pulp sheet was characterized by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and ATR to provide evidence for product synthesis.


      PubDate: 2014-12-20T11:29:02Z
       
  • An emerging approach for the targeting analysis of dimethoate in olive
           oil: The role of molecularly imprinted polymers based on photo-iniferter
           induced “living” radical polymerization
    • Abstract: Publication date: January 2015
      Source:Reactive and Functional Polymers, Volume 86
      Author(s): Nuno Martins , Elisabete P. Carreiro , Marco Simões , Maria João Cabrita , Anthony J. Burke , Raquel Garcia
      This study concerns the first attempt to prepare molecularly imprinted polymers for the selective recognition of dimethoate using an iniferter polymerization technique (Inif-MIP). The synthesized polymers were fully characterized. SEM micrographs show a large accessibility to the binding sites with a significant improvement in MIP morphology. Inif-MIPs displayed high adsorption capacity (Q =5.3mgg−1). The selectivity of this imprinting system was also assessed by means of cross-selectivity assays and the results obtained show that Inif-MIP displays a high selectivity for dimethoate, whereas some structural analogues (omethoate, malathion and methidathion) are poorly retained (6.3–28.7%) or not retained at all (fenthion). Inif-MISPE methodology was implemented by packing Inif-MIPs particles into a Solid Phase Extraction (SPE) cartridge and the loading, washing and eluting steps were optimized. The suitability of this sample preparation technique was demonstrated, as concentrations of dimethoate close to the tolerated maximum residue limits in the olive oil samples could be satisfactorily analyzed with good precision and accuracy. Some remarkable characteristics, like the sorbent reusability (at least 20 cycles without the lost of selectivity), low solvent consumption, reduced sample handling and, moreover higher recovery rates reaching 88% could be ascribed to the Inif-MISPE methodology.


      PubDate: 2014-12-20T11:29:02Z
       
  • Dual-responsive polymer–drug nanoparticles for drug delivery
    • Abstract: Publication date: January 2015
      Source:Reactive and Functional Polymers, Volume 86
      Author(s): Mong Liang , Tsung-Min Yang , Hui-Ping Chang , Yu-Min Wang
      A well-defined, dual temperature- and pH-responsive drug carrier was synthesized through the radical copolymerization of methacrylic acid, N-isopropylacrylamide, and an N-(methacryloyl)glycylglycine 4-nitrophenyl ester. When the anticancer agent gemcitabine or antibiotic sulfamethoxazole was conjugated with a polymer and heated beyond its low critical solution temperature (40°C), a dual temperature- and pH-induced phase transition was observed. This temperature was considered ideal for activating drug aggregation under hyperthermic and acidic conditions. The structure and properties of polymer drugs were investigated using nuclear magnetic resonance, Fourier transform infrared spectrometry, ultraviolet–visible absorption, transmission electron microscopy, and gel permeation chromatography. At a critical micelle concentration of 1mg/mL, both polymer drugs formed micellar structures with diameters ranging from 50nm to 150nm, based on TEM image. These micelles exhibited higher pharmacological efficacy than the free drug alone did, and the cytotoxicity at the target site was substantially enhanced compared with that of the polymer–drug conjugate formed under normal physiological conditions.


      PubDate: 2014-12-20T11:29:02Z
       
  • Synthesis of soy protein–lignin nanofibers by solution
           electrospinning
    • Abstract: Publication date: December 2014
      Source:Reactive and Functional Polymers, Volume 85
      Author(s): Carlos Salas , Mariko Ago , Lucian A. Lucia , Orlando J. Rojas
      Nanofibers were produced by electrospinning aqueous alkaline solutions containing different mass ratios of soy protein and lignin in the presence of poly(ethylene glycol) coadjutant, all of which presented shear thinning behavior. SEM revealed that the addition of polyethylene oxide as a coadjutant indeed facilitated the formation of defect-free fibers whose diameter increased with lignin concentration, in the range between ≈124 and ≈400nm. Favorable interactions between lignin and soy protein were identified from data provided by differential scanning calorimetry. In addition, an increased hydrogen bonding and the loss of secondary structure of the proteins as the lignin concentration increased were observed from the disappearance of amide II (∼1500cm−1) and III (∼1400–1200cm−1) bands and a red shift of amide I band in the FT-IR spectrum. The unfolding of the protein contributed to a better interaction with lignin macromolecules, which further improved the electrospinning process. It is concluded that mixtures of lignin and soy proteins, two major renewable resources with interesting chemical features, are suitable for the development of composite sub-micron fibers.
      Graphical abstract image

      PubDate: 2014-12-20T11:29:02Z
       
  • Towards continuous junction (CJ) organic electronic devices: Fast and
           clean post-polymerization modification by oxidation using
           dimethyldioxirane (DMDO)
    • Abstract: Publication date: January 2015
      Source:Reactive and Functional Polymers, Volume 86
      Author(s): Florian Glöcklhofer , Daniel Lumpi , Markus Kohlstädt , Olena Yurchenko , Uli Würfel , Johannes Fröhlich
      An advanced design concept for organic electronic devices relying on functional polymers is presented. The concept aims at realizing a gradual transition from an electron-donating to an electron-accepting material in a specific post-polymerization modification step. Hence, this approach facilitates a straight forward fabrication compared to conventional multi-layer architectures. The synthesis via microwave-assisted Cu(I)-catalyzed azide–alkyne cycloaddition of the reactive polymers based on sulfur, selenium and tellurium as active sites is presented; full characterization of model compounds and polymers is provided. Additionally, a reliable procedure for post-polymerization oxidation applying dimethyldioxirane is developed. Photophysical and electrochemical characteristics of the novel polymers reveal the feasibility but also the challenges of the continuous junction concept.


      PubDate: 2014-12-20T11:29:02Z
       
  • Chemically modified organic/inorganic nanoporous composite particles for
           the adsorption of reactive black 5 from aqueous solution
    • Abstract: Publication date: January 2015
      Source:Reactive and Functional Polymers, Volume 86
      Author(s): Ali Nematollahzadeh , Akbar Shojaei , Mehdi Karimi
      In the present work, we report a chemically modified polyacrylamide/silica nanoporous composite adsorbent for the removal of reactive black 5 (RB5) azo dye from aqueous solutions. The composite adsorbent was synthesized in a packed bed and modified by ethylenediamine (EDA). The adsorbent was characterized by Fourier transformation infrared (FT-IR), thermogravimetric analysis (TGA), thermoporometry, Brunauer, Emmett and Teller (BET) method and scanning electron microscopy (SEM). Mechanical stability of the adsorbent was examined in a packed bed by following the back-pressure of the column. Pore diameter of the composite adsorbent in dry and wet states was estimated to be about 18.71nm and 12.61nm, respectively. Adsorption experiments were performed in batch mode and effect of various operational parameters on the adsorption capability of the adsorbent was studied systematically. The maximum adsorption capacity of the modified composites was found to be 454.5mg RB5/g of adsorbent. The equilibrium data were analyzed by Langmuir, Freundlich, Sips, BET and Redlich–Peterson isotherm models and found to fit well to the BET isotherm. The data kinetically followed the pseudo-second-order model. High adsorption capacity, fast removal mechanism, and good mechanical stability are three advantages of the presented composite for the removal of RB5.


      PubDate: 2014-12-20T11:29:02Z
       
  • Preparation of cellulose-based conductive hydrogels with ionic liquid
    • Abstract: Publication date: January 2015
      Source:Reactive and Functional Polymers, Volume 86
      Author(s): Xiangtao Liang , Bing Qu , Junrong Li , Huining Xiao , Beihai He , Liying Qian
      Conductive hydrogel composed of microcrystalline cellulose (MCC) and polypyrrole (PPy) was prepared in ionic liquid; and the resulting hydrogel was characterized with FT-IR, SEM, XRD and TGA. By doping with TsONa, the MCC/PPy composite hydrogels showed relatively high electrical conductivity, up to 7.83×10− 3 S/cm, measured using a four-probe method. The swelling kinetics of the composite hydrogels indicated that the swelling process was mainly influenced by the cellulose content; and the equilibrium swelling ratio decreased as the increasing of MCC content in the hydrogels. In addition, the MCC/PPy composite hydrogels exhibited significantly enhanced mechanical property in contrast to MCC hydrogel.


      PubDate: 2014-12-20T11:29:02Z
       
  • Quantification of singlet oxygen generation from photodynamic hydrogels
    • Abstract: Publication date: Available online 6 December 2014
      Source:Reactive and Functional Polymers
      Author(s): Rebecca A. Craig , Colin P. McCoy , Áine T. De Baróid , Gavin P. Andrews , Sean P. Gorman , David S. Jones
      Recently, we described a series of novel porphyrin-impregnated hydrogels capable of producing microbicidal singlet oxygen (1O2) on photoactivation. Indirect assessment of the efficacy of 1O2 production from such hydrogels has been previously described using microbiological techniques, but here we report a novel, direct method of quantification. Anthracene-9,10-dipropionic acid (ADPA) is known to irreversibly form an endoperoxide on reaction with 1O2, causing photobleaching of its absorbance band at approximately 378 nm. Here, the reaction of this probe is exploited in a novel way to provide a simple, inexpensive, and convenient measurement of 1O2 generation from the surface of porphyrin-incorporated photosensitising hydrogels, with the ability to account for effects due to hydrogel porosity. Ingress of the probe into the materials was observed, with rates of up to 3.83 x 103 s-1. This varied by up to 200-fold with material composition and surface modification. Rates of 1O2 generation in these porphyrin-incorporated hydrogels, after compensating for ADPA ingress, ranged from 1.86x103 – 5.86x103 s-1. This work demonstrates a simple and straightforward method for direct 1O2 quantification from porous materials, with general utility.


      PubDate: 2014-12-20T11:29:02Z
       
 
 
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